Albedo

 

 What is Albedo

   Albedo is known as surface reflectivity of sun’s radiation. The term has its origins from a Latin word albus, meaning “white”. It is quantified as the proportion, or percentage of solar radiation of all wavelengths reflected by a body or surface to the amount incident upon it. An ideal white body has an albedo of 100% and an ideal black body, 0%. The typical amounts of solar radiation reflected from various objects are shown in Table 1. Albedo values can range between 3% for water at small zenith angles to over 95% for fresh snow. On average the Earth and itsatmosphere typically reflect about 4% and 26%, respectively, of the sun’s incoming radiation back to space over the course of one year. As a result, the earth-atmosphere system has a combined albedo of about 30%, a number highly dependent on the local surface makeup, cover, and cloud distribution

 Definition provided by Encyclopedia of the Earth

 Albedo and global warming

    Lets consider what Albedo value really means, higher Albedo value means most of the incoming photons are reflected out into the universe.  So most of the energy coming from the sun is actually reflected out.  If the albedo value lower then most of the energy coming from sunshine is absorbed.  So what does this have to do with global warming?   Well the Earth has an average of .30, so 30% of the light energy is reflected out, and 70% is absorbed by the Earth.  If the polar caps melt then the then the we lose large sections of the surface area of the Earth that reflects between 30% to 95% of the light the light that hits, which in turn will raise the average Albedo of the Earth, and in turn heat up the Earth.  But the worse part is that we will lose land mass and ice fields and replace it with water, which absorbs almost all light energy that hits it.